MODERN MONETARY THEORY SHOWS HOW FULL EMPLOYMENT CAN BE ACHIEVED!

POTENTIAL GDP is a level of overall spending - by the government and the non-government sector - at which there is full employment. If the economy is not operating at its potential, then the  private sector has failed to invested or spend enough to generate the necessary growth nor has income  from net exports contributed enough. This only leaves the government to close the spending gap. Conceptually, a government disposing of its own freely floating currency could act using two powerful tools -  spending in excess of tax revenue, and taxation - to ensure that the gap between the actual economic activity and potential GDP is quickly closed. Achieving the  full employment that prevailed for 30 years between 1945 and 1975 in western economies is definitely possible! 

The economy is a self-organizing system that needs continuous growth and a constant inflow of energy and materials in order to maintain itself.  Absence of growth will make the system fragile, and economic contraction could lead very quickly to its collapse. These are characteristics of dissipative systems that apply to the free market economy. Another characteristic is that economic activity will unavoidably lead to the generation of waste heat, greenhouse gases and waste materials that the system must expel into its environment, making the system unviable in the present context of global warming and increasing oil prices.

The simplified graphic representation of the economy shows how it is basically profits that generate the funds for the resources needed to guarantee that the system can continue to grow. Loans do not fulfil this function, since loans must be repaid from profit and credit institutions will be reluctant to extend loans if they fear their profits are endangered by the inability of creditors to generate enough income to meet interest payments. So the system depends on private companies and blind market forces. However, society can no longer rely on a system that is blindly guided by the profit motive and that is to a large degree responsible for much of the environmental problems that now afflict us. The system cannot continue in its present self-reinforcing growth mode. Governments can and must step in to fulfil their responsibility and fundamentally reform a system that has become harmful and that is driven exclusively by profit.

Goodwin cycle IM-2010 with debt and taxes added, modified from Steve Keen's illustration of Hyman Minsky's Financial Instability Hypothesis "stability begets instability". This can be extended by adding the Ponzi effect of borrowing for speculative investment.